STATION 1.
LAGUNA CREEK WATERSHED
A
watershed or drainage basin refers to a system controlled by topography,
which defines how water will flow. You refer to a watershed by the largest body
of water that the creeks, rivers or streams feed into. For example, all creeks
that flow in the San Francisco Bay are part of the San Francisco Watershed.
However, there are many smaller watersheds within this area depending on flow
patterns. Laguna Creek Watershed would be an area that drains into Laguna
Creek.
Passing in front
of Station 1 is Mission Creek which is flowing from the Mission San Jose area.
Mission Creek actually joins Morrison Creek at the northeast of Lake
Elizabeth. Mission Creek does not really drain into Lake Elizabeth, but
is used to control the height of the lake. Lake Elizabeth is an artificial lake
created not only for recreational purposes but to control flood conditions.
Muskrat Creek, which flows through the Stivers Lagoon Nature Trail, flows
into Mission just northwest of the Gazebo.
Mission Creek flows under Paseo Padre and splits into two creeks.
Laguna Creek, toward the southeast, is the historic path of the creek,
but is now the high flow drainage during a storm. It dries up during most of the dry season.
Irvington Creek toward the southwest flows all year round from Paseo
Padre along Grimmer until it meets with Laguna Creek near the 880 freeway.
Notice along Mission Creek the type of vegetation. These sandbar and narrow-leaf willows help to stabilize the bank from erosion. Willows are common along creeks because their roots can tolerate water. Plant cover is important to a watershed to prevent the erosion of valuable soil as water rushes downstream. Plant cover also provides food and protection for many small organisms.
The green zone along a stream ecosystem is called a riparian area and has several unique properties. Riparian zones have the capacity to buffer rivers and other waters from runoff from agricultural, urban, or other areas. Healthy riparian zones can absorb sediments, chemical nutrients, and other substances contained in runoff.
Throughout watersheds natural mechanisms can help clean water through filtration as it flows in the system. However, we sometimes pollute these watersheds through industrial or municipal waste discharging into the watershed (point source pollution). This overloads the systems and pollution increases. Even non-point source pollution (many sources to pollution) can accumulate and cause as much damage. Our watersheds reflect the health of our environment. Water that migrates through the different levels of the watershed nourishes biological life.
LESSON. Identification of willow -
Instruct students to look at the leaves of the different willows in
the area. Notice they are long and
thin. During the spring the willows
have male and female catkins which hang from the stems.
Catkins help to identify the different species.
LESSON.
Identification of Native Grasses - Use the appendix at the end of this guide to help identify the
different grasses. Saltgrass is a
native grass found near the gazebo. Most
of the other grasses are non-native.
LESSON. Identification of Flora - During the spring the meadow in
this region is full of different flowers. Use
the appendix to help identify the plants. You may want to press some of the leaves so you can identify
them in the classroom. You can take
leaves and tape them on an index card, as a quick way to preserve the leaves.
As you walk
between station 1 and 2 you will notice a group of trees to the right.
Most of the these trees and shrubs are not native to this area.
The seeds for these plants probably came from ornamentals that have been
planted throughout the city.